Poison ivy is Brookline man's passion

"There's poison ivy everywhere!" is normally a statement uttered in disgust, fear or even panic. For Jon Sachs, it is an exclamation of joy.

"Look at this," he says pointing to a couple of dead trees along the Fresh Pond reservoir in Cambridge with an abundance of green leaves covering every branch. "It's amazing how adaptable this stuff can be. More than half of the vegetation around this reservoir is poison ivy."

Sachs, 58, is a leading specialist on Toxicodendron radicans, though he's not one for Latin names. He runs the Internet's most popular website devoted to poison ivy, though he's not a scientist (he spent his undergraduate days at MIT studying filmmaking and photography). And he's not a peddler of anti-itch lotions and creams, though ads from those who do are what keep poison-ivy.org in business.

The Brookline resident is an accidental enthusiast with a very traditional poison ivy story: it started with an unintentional encounter and has turned into a long-term itch.

It began seven years ago when Sachs and Walter, his 12-year-old black Labrador, were walking in the woods so that Sachs could pursue his passion for nature photography. When he stumbled upon a perfect example of a three-leafed poison ivy plant, he bent down to snap a photo. That's when the Russian family walked up.

"They were very interested in what I was doing, because they had heard of poison ivy but didn't know what it looked like," he said.

A light bulb went off in his head. Sachs owns his own design company, where he creates websites for clients, and had been toying with the idea of creating his own site. When it occurred to him that not many people can identify poison ivy, he started the site and began selling posters and cards to help people spot it and avoid it.

Sachs was uniquely suited to the task because he had developed in childhood what he calls "a strong visual target" for picking poison ivy out of a crowd, "the way golfers are good at finding golf balls," he said. "Fifty years later, I can still spot it driving down the turnpike."

Glenn Adelson, a frequent field companion of Sachs and a former lecturer in biology and environmental science at Harvard, says that while Sachs is self-trained, his knowledge is top-shelf.

"He's become as good as anyone at being able to pick it out, especially distinguishing it from look-alikes," said Adelson, who will be an assistant professor of biology at Wellesley in the fall. "He never makes a mistake, and he notices very particularly the variation in the plants."

That ability has come in handy for the hundreds of people who have e-mailed Sachs garden photos asking "Is this it?"

Sachs says the traditional description of poison ivy, three shiny leaves with white berries, is inadequate to encompass the plant's variability.

Most startling, according to Sachs, is the increase in leaf size since his childhood. A study published in the current issue of the journal Weed Science has found that the CO{-2} loving plant has doubled in size since 1950 and it has become more potent.

As he and Walter made their way slowly around the reservoir Sachs pointed out shiny leaves, flat leaves, notched leaves, round leaves, red stems, and green stems, all loaded with the urushiol oil that will "make you itch like you wouldn't believe," he said.

That itch is the other thing people contact him about. He gets desperate e-mails from people who want to make it go away. (He recommends rinsing with cold water immediately after contact and thinks soap only makes the itch worse.)

There was the wife who wanted to know whether her husband's rash -- which started on his hands and spread to more sensitive areas -- would affect their love life. "I told them what I thought they should do," he said. "I never heard from her again, so I guess it worked."

Then there are those who want to commiserate. His website features a "Poison Ivy Rash Hall of Fame" for when it's just so bad you have to share.

Sachs admits that being the "poison ivy guy" is a quirky thing. But as long as he and Walter continue taking their long walks in search of new varieties in the poison ivy story -- Sachs recently photographed a rare five-leaf specimen -- he can handle the occasional raised eyebrow from his girlfriend.

"The worst thing that can happen is you don't get a great picture," he said. "But me and Walter still have a good time."

Hometown: Mahopac, N.Y.; lives in Brookline

Education: Bachelor's of science in art and design from MIT in 1971, where he studied filmmaking and photography.

Family: Two brothers, Daniel, 61, an acupuncturist in Gill, and Frederick, 67, a research scientist in Buffalo.

Hobbies: Has been making his annual "Walter the Dog" calendar for family and friends for 10 years.

On being an art student at MIT in the late 60's and early 70's: "I suspect that I really didn't belong at MIT. But if I'd gone to art school in the drug years, who knows if I would have survived all that."